Method for forming copper-based film and material for forming copper-based film

ABSTRACT

The present invention is directed to a method for forming a copper-based film on a substrate in supercritical fluid, wherein (N,N′-Diisopropylpropion amidinate) copper dimer is dissolved in supercritical fluid and copper is deposited on the substrate to form the copper-based film thereon.

TECHNICAL FIELD

The present invention relates to a technology for forming a copper-basedfilm.

BACKGROUND ART

Films made of, for example, copper or copper alloy (hereinaftercollectively referred to as copper) are employed in various kinds offields. For example, the films are employed in a field of ULSI for thepurpose of providing wiring films. An electrolytic plating method, asputtering method, a CVD method, an ALD method, or a SCFD (SupercriticalFluid Deposition) method is proposed for producing copper wirings. Theelectrolytic plating method and the sputtering method are in practicaluse. However, it is said that it is hard to produce wiring films havinga wiring width of a nano-scale by the electrolytic plating method andthe sputtering method. The CVD method, the ALD method, and the SCFDmethod are expected for the formation of a film onto a deep groove (orhole) with an opening having a nano-scale width. In the CVD method andthe ALD method, vaporization (gasification) of a starting material isessential. To the contrary, in the SCFD method, gasification is notrequired but only dissolving of the starting material in supercriticalfluid is required. In this point, there is a difference in conditionbetween the starting material to be used in the CVD method and the ALDmethod and the starting material to be used in the SCFD method.

The following Non-patent Literatures are known as the technology forforming the copper film by the SCFD method.

CITATION LIST Non-Patent Literature [NON-PATENT LITERATURE 1]

Journal of Jpn. J. Appl. Phys. 2005, 44, L1199-L1202. Takeshi Momose,Masakazu Sugiyama and Yukihiro Shimogaki “Precursor Evaluation forCu-Supercritical Fluid Deposition Based on Adhesion Properties andSurface Morphology”

[NON-PATENT LITERATURE 2]

Journal of Electrochemical Society, 2009, 156, 6, H44341447. MasahiroMatsubaraa, Michiru Hirosea, Kakeru Tamaia, Yukihiro Shimogaki andEiichi Kondoha“Kinetics of Deposition of Cu Thin Films in SupercriticalCarbon Dioxide Solutions from a F-Free Copper(II)-Diketone Complex”

Patent Literature [PATENT LITERATURE] US7241912B2 SUMMARRY OF INVENTIONTechnical Problem

In the above Non-patent Literatures, β-diketone copper complexes such asa complex of (hexafluoroacetylacetonato)copper [Cu(hfac)₂] and a complexof (diisobutylmethanato) copper [Cu(dibm)₂] were used to performdeposition of copper (formation of a copper film) in supercritical fluidof CO₂. As a result thereof, a copper film was formed by the SCFDmethod.

However, thus obtained copper film contained a large amount ofimpurities.

A cause thereof was searched.

As a result of the search, the inventors came to know that chemicalcompounds such as Cu(hfac)₂ and Cu(dibm)₂ require high temperature inorder to be decomposed in the supercritical fluid. The inventorspresumed that β-diketone of a ligand was decomposed therein and,therefore, C and O were contaminated in the copper film.

Further, in a case where the Cu(hfac)₂ was used, F was detected in thecopper film. Contamination of F in the copper film induced deteriorationof adhesion between a base film and the copper film.

Accordingly, the inventors came to know that solution of startingmaterial in the supercritical fluid is not the only requirement in theSCFD method.

However, it is still essential to dissolve the starting material in thesupercritical fluid.

Under the circumstances, the present invention is made to solve theabove problems. Specifically, the present invention is made to provide atechnology for forming a high quality copper film with ease. With thetechnology, decomposition temperature in the supercritical fluid is lowand degradation of quality of the copper film due to contamination of Cand/or O can be improved.

Solution to Problem

The inventors have conducted intensive studies in order to solve theabove problems.

As a result thereof, the inventors came to know that, in a case where achemical compound (copper amidinate complex), being dissolved in thesupercritical fluid, represented by the following General Formula [I] isused to perform a deposition reaction, the amount of contamination ofthe impurities (C, O) in the deposition film is small and, therefore, ahigh quality Cu-based film is stably formed in the groove (or the hole)of a nano-scale.

The above listed Patent Literature discloses a chemical compound (metalamidinate complex) represented by the following General Formula [I].

However, the above listed Patent Literature is silent on a technology ofdissolving the chemical compound represented by the following GeneralFormula [I] in the supercritical fluid and depositing copper on asubstrate.

In addition to the above, the inventors of the present invention believethat a scientist (technical expert) having ordinary knowledge in thisfield had no idea to dissolve a Cu amidinate complex in thesupercritical fluid (e.g., CO₂) and deposit copper on the substrate.

The metal amidinate complex is known by its property of being decomposedimmediately in the air. For example, a Li amidinate complex, an Naamidinate complex, a K amidinate complex, a Mg amidinate complex, a Caamidinate complex, a Sr amidinate complex, a Ba amidinate complex, a Tiamidinate complex, a V amidinate complex, a Cr amidinate complex, a Mnamidinate complex, a Fe amidinate complex, a Co amidinate complex, an Niamidinate complex, a Zn amidinate complex, a Cd amidinate complex, and aSn amidinate complex are known as having the property of beingimmediately decomposed in the air. Further, the metal amidinate complexis known by a property of reacting with ketone (e.g., acetone and methylisobutyl ketone) and CO₂.

In view of the above, the inventors of the present invention believethat a scientist (technical expert) having ordinary knowledge in thisfield had no idea to dissolve a Cu amidinate complex in thesupercritical fluid (e.g., CO₂) and deposit copper on the substrate.

However, the inventors of the present invention found that the Cuamidinate complex represented by the following General Formula [I]dissolves in ketone and CO₂ as well as that no reaction is producedtherebetween.

The present invention was made based on the above knowledge.

The present invention proposes a material for forming a copper-basedfilm on a substrate by decomposing a chemical compound dissolved insupercritical fluid, wherein the chemical compound is a chemicalcompound represented by the following General Formula [I].

The present invention proposes a method for forming a copper-based filmon a substrate in supercritical fluid, wherein a chemical compoundrepresented by the following General Formula [I] is dissolved insupercritical fluid and copper is deposited on the substrate to form acopper-based film thereon.

[Each of R¹, R², R³, R⁴, R⁵, and R⁶ is a hydrocarbon group having acarbon number of 1 to 10. The R¹, R², R³, R⁴, R⁵, and R⁶ maybe the sameor may be different from one another.]

Advantageous Effect of Invention

According to the present invention, it is possible to stably form a highquality Cu-based film (e.g., a film containing little impurities such asC and O) in a groove (or a hole) of a nano-scale.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic drawing of a SCFD system.

FIG. 2 is an electron micrography.

FIG. 3 is another electron micrography.

DESCRIPTION OF EMBODIMENTS

A first invention is directed to a method for forming a copper-basedfilm. The method is a method in which a chemical compound represented bythe following General Formula [I] is dissolved in supercritical fluidand copper is deposited on a substrate to form a copper-based filmthereon.

A second invention is directed to a material for forming a copper-basedfilm. The material is a material for forming a copper-based film on asubstrate by decomposing a chemical compound dissolved in supercriticalfluid. The chemical compound is a chemical compound represented by thefollowing General Formula [I].

[Each of R¹, R², R³, R⁴, R⁵, and R⁶ is a hydrocarbon group having acarbon number of 1 to 10. The hydrocarbon group may be an aliphatichydrocarbon group or may be an aromatic hydrocarbon group. Thehydrocarbon group may have a substituent or may not have a substituent.The substituent may be a functional group having Si. The R¹, R², R³, R⁴,R⁵, and R⁶ may be the same or may be different from one another.Preferably, R¹, R², R⁴, and R⁵ differ from R³ and R⁶.

The chemical compound represented by the General Formula [I] is a solidin many cases. In a case where the chemical compound is a solid, it ismore preferred to supply the chemical compound to the supercriticalfluid, with the chemical compound being dissolved in a solvent (in asolution form), than to supply the chemical compound as it is to thesupercritical fluid in order to well dissolve the chemical compound inthe supercritical fluid. The solvent may be any solvent in so far as thesolvent does not adversely effects on the chemical compound and thesupercritical fluid. Preferable solvent is one or more selected fromketone (e.g., acetone, methylethyl ketone, methylpropyl ketone, methylisobutyl ketone, methyl amyl ketone, diethyl ketone, and cyclohexanone),ether (e.g., diethyl ether, tetrahydrofuran, and dioxane), andhydrocarbon (e.g., pentane, hexane, heptanes, octane, nonane, anddecane). The hydrocarbon may be any one of straightly chained aliphatichydrocarbon, aliphatic hydrocarbon having branched chain, or cyclichydrocarbon.

The most preferable chemical compound as the chemical compound that isrepresented by the General Formula [I] has such a structure that each ofR¹, R², R⁴, and R⁵ is an iso-propyl group, and each of R³ and R⁶ is anethyl group (i.e., (N,N′-Diisopropylpropionamidinate) copper dimer).

A preferable chemical compound as the chemical compound that isrepresented by the General Formula [I] has such a structure that each ofR¹, R², R⁴, and R⁵ is an iso-propyl group, and each of R³ and R⁶ is amethyl group (i.e., (N,N′-Diisopropylacetoamidinate) copper dimer).

A preferable chemical compound as the chemical compound that isrepresented by the General Formula [I] has such a structure that each ofR¹, R², R⁴, and R⁵ is an iso-propyl group, and each of R³ and R⁶ is ann-butyl group (i.e., amidinate copper).

A preferable chemical compound as the chemical compound that isrepresented by the General Formula [I] has such a structure that each ofR¹, R², R⁴, and R⁵ is an n-propyl group, and each of R³ and R⁶ is amethyl group (i.e., amidinate copper).

A preferable chemical compound as the chemical compound that isrepresented by the General Formula [I] has such a structure that each ofR¹, R², R⁴, and R⁵ is an n-propyl group, and each of R³ and R⁶ is anethyl group (i.e., amidinate copper).

A preferable chemical compound as the chemical compound that isrepresented by the General Formula [I] has such a structure that each ofR¹, R², R⁴, and R⁵ is an n-propyl group, and each of R³ and R⁶ is ann-butyl group (i.e., amidinate copper).

A preferable chemical compound as the chemical compound that isrepresented by the General Formula [I] has such a structure that each ofR¹, R², R⁴, and R⁵ is an n-butyl group, and each of R³ and R⁶ is amethyl group (i.e., amidinate copper).

A preferable chemical compound as the chemical compound that isrepresented by the General Formula [I] has such a structure that each ofR¹, R², R⁴, and R⁵ is an n-butyl group, and each of R³ and R⁶ is anethyl group (i.e., amidinate copper).

A preferable chemical compound as the chemical compound that isrepresented by the General Formula [I] has such a structure that each ofR¹, R², R⁴, and R⁵ is an iso-butyl group, and each of R³ and R⁶ is amethyl group (i.e., amidinate copper).

A preferable chemical compound as the chemical compound that isrepresented by the General Formula [I] has such a structure that each ofR¹, R², R⁴, and R⁵ is an iso-butyl group, and each of R³ and R⁶ is anethyl group (i.e., amidinate copper).

A preferable chemical compound as the chemical compound that isrepresented by the General Formula [I] has such a structure that each ofR¹, R², R⁴, and R⁵ is an iso-butyl group, and each of R³ and R⁶ is ann-butyl group (i.e., amidinate copper).

A preferable chemical compound as the chemical compound that isrepresented by the General Formula [I] has such a structure that each ofR¹, R², R⁴, and R⁵ is a sec-butyl group, and each of R³ and R⁶ is amethyl group (i.e., amidinate copper).

A preferable chemical compound as the chemical compound that isrepresented by the General Formula [I] has such a structure that each ofR¹, R², R⁴, and R⁵ is a sec-butyl group, and each of R³ and R⁶ is anethyl group (i.e., amidinate copper).

A preferable chemical compound as the chemical compound that isrepresented by the General Formula [I] has such a structure that each ofR¹, R², R⁴, and R⁵ is a sec-butyl group, and each of R³ and R⁶ is ann-butyl group (i.e., amidinate copper).

A preferable chemical compound as the chemical compound that isrepresented by the General Formula [I] has such a structure that each ofR¹, R², R⁴, and R⁵ is a phenyl group, and each of R³ and R⁶ is a methylgroup (i.e., amidinate copper).

A preferable chemical compound as the chemical compound that isrepresented by the General Formula [I] has such a structure that each ofR¹, R², R⁴, and R⁵ is a phenyl group, and each of R³ and R⁶ is an ethylgroup (i.e., amidinate copper).

When a certain substance is placed under the temperature more than acritical point and the pressure more than a critical point, thephenomenon of supercritical fluid will appear. Supercritical fluid isfluid in a state where discrimination is not made between gas and afluid. Supercritical fluid has both of the diffusibility of gas and thesolubility of a fluid. CO₂ becomes supercritical fluid under theconditions of a temperature of 304.1K or more and a pressure of 7.38 MPaor more. H₂O becomes supercritical fluid under the conditions of atemperature of 647.3K or more and a pressure of 22.12 MPa or more. CH₁becomes supercritical fluid under the conditions of a temperature of190.4K or more and a pressure of 4.60 MPa or more. C₂H₆ becomessupercritical fluid under the conditions of a temperature of 305.3K ormore and a pressure of 4.87 MPa or more. C₂H₄ becomes supercriticalfluid under the conditions of a temperature of 282.4K or more and apressure of 5.04 MPa or more. CH₃CH₂OH becomes supercritical fluid underthe conditions of a temperature of 513.9K or more and a pressure of 6.14MPa or more. CH₃COCH₃ becomes supercritical fluid under the conditionsof a temperature of 508.1K or more and a pressure of 4.70 MPa or more.In the present invention, any one of the above described supercriticalfluids may be used. Here, preferable supercritical fluid contains CO₂.More preferable supercritical fluid is a mixture of CO₂ and H₂.

Hereinafter, more specific examples will be described. However, thepresent invention will not be limited to the examples described below.All modifications and applications which do not depart from the spiritand scope of the present invention are deemed to be covered by theinvention.

Example 1 Deposition of Copper in Supercritical Fluid of CO₂ Using a(N,N′-Diisopropylpropion Amidinate) Copper Complex

FIG. 1 is a schematic drawing of a SCFD apparatus which performs acopper-based film forming method according to the present invention.

In FIG. 1, 1 denotes a CO₂ high pressure cylinder, 2 denotes a H₂ highpressure cylinder, 3 denotes a cooling device, 4 denotes pressure pumps(10 MPa), 5 denotes a mixer, 6 denotes a container, 7 denotes heaters, 8denotes a preheating chamber, 9 denotes a reaction chamber, 10 denotes asubstrate (a silicon substrate provided with a ruthenium thin film), and11 denotes a back pressure governor.

An acetone solution (concentration of 3.34×10⁻⁵ mol) of the(N,N′-Diisopropylpropion amidinate) copper dimer (In the General Formula[I], R¹═R²═R⁴=R⁵═—CH(CH₃)₂, R³═R⁶═—CH₂CH₃) is placed in the container 6.

The reaction chamber 9 is kept at a temperature of 140° C. by theheaters 7. The reaction chamber 9 is kept at 13 MPa by supercriticalfluid (CO₂+H₂). A partial pressure of CO₂ was 12 MPa, and a partialpressure of H₂ was 1 MPa.

The acetone solution of the (N,N′-Diisopropylpropion amidinate) copperdimer was supplied to the reaction chamber 9 using the pumps 4. In otherwords, the (N,N′-Diisopropylpropion amidinate) copper dimer was suppliedto the supercritical fluid. The supercritical fluid containing thechemical compound represented by the General Formula [I] was supplied toa surface of the substrate 10. The chemical compound of the GeneralFormula [I] was decomposed. This achieved deposition of copper film onthe surface. The substrate 10 was taken out after 15 minutes from thestart of supply of the starting material. A film of a copper color wasformed on the taken out substrate 10.

The substrate 10 was subjected to an EDS analysis (Energy dispersiveX-ray spectrometry). As a result of the analysis, no C or O was observedin the film formed on a surface of the substrate 10. By an X-raydiffraction, it was found that the film was a copper thin film in whichthe copper is mainly oriented to (111). With the use of the electronmicroscope, it was found that an inside of the groove (having a width of140 nm and a depth of 1.6 μm) formed in the substrate 10 was completelyfilled with copper (see, FIG. 2).

Example 2

A copper-based film forming method was carried out in a manner identicalto that performed in Example 1 except that the heating temperature bythe heaters 7 was changed from 140° C. to 160° C. A result similar tothat of Example 1 was obtained (see, FIG. 3). Generally, as thetemperature becomes higher, the embeddability becomes poorer. However,as the temperature becomes higher, the throughput becomes better. Thepresent example shows that good embeddability was achieved even at atemperature of 160° C.

Example 3

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 except that n-pentane wasemployed instead of acetone. A result similar to that of Example 1 wasobtained. However, the (N,N′-Diisopropylpropion amidinate) copper dimerindicated solubility poorer than the case of Example 1. In other words,in the present example, a concentration of the chemical compound(General Formula [I]) in the solution was low. Therefore, it took about20% longer time for the deposition of a copper film than the case ofExample 1.

Example 4

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 except that cyclohexane wasemployed instead of acetone. A result similar to that of Example 1 wasobtained. However, the (N,N′-Diisopropylpropion amidinate) copper dimerindicated solubility poorer than the case of Example 1. In other words,in the present example, a concentration of the chemical compound(General Formula [I]) in the solution was low. Therefore, it took about20% longer time for the deposition of a copper film than the case ofExample 1.

Example 5

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 except that n-heptane wasemployed instead of acetone. A result similar to that of Example 1 wasobtained. However, the (N,N′-Diisopropylpropion amidinate) copper dimerindicated solubility poorer than the case of Example 1. In other words,in the present example, a concentration of the chemical compound(General Formula [I]) in the solution was low. Therefore, it took about20% longer time for the deposition of a copper film than the case ofExample 1.

Example 6

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 except that n-octane wasemployed instead of acetone. A result similar to that of Example 1 wasobtained. However, the (N,N′-Diisopropylpropion amidinate) copper dimerindicated solubility poorer than the case of Example 1. In other words,in the present example, a concentration of the chemical compound(General Formula [I]) in the solution was low. Therefore, it took about20% longer time for the deposition of a copper film than the case ofExample 1.

Example 7

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 except that n-nonane wasemployed instead of acetone. A result similar to that of Example 1 wasobtained. However, the (N,N′-Diisopropylpropion amidinate) copper dimerindicated solubility poorer than the case of Example 1. In other words,in the present example, a concentration of the chemical compound(General Formula [I]) in the solution was low. Therefore, it took about20% longer time for the deposition of a copper film than the case ofExample 1.

Example 8

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 except that n-decane wasemployed instead of acetone. A result similar to that of Example 1 wasobtained. However, the (N,N′-Diisopropylpropion amidinate) copper dimerindicated solubility poorer than the case of Example 1. In other words,in the present example, a concentration of the chemical compound(General Formula [I]) in the solution was low. Therefore, it took about20% longer time for the deposition of a copper film than the case ofExample 1.

Example 9

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 except that methyl isobutylketone was employed instead of acetone. A result similar to that ofExample 1 was obtained.

Example 10

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 except that diethyl ether wasemployed instead of acetone. A result similar to that of Example 1 wasobtained. However, 0 was slightly observed in a Cu-based film in the EDSanalysis.

Example 11

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 except that tetrahydrofuran wasemployed instead of acetone. A result similar to that of Example 1 wasobtained. However, 0 was slightly observed in a Cu-based film in the EDSanalysis.

Example 12

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 except that dioxane wasemployed instead of acetone. A result similar to that of Example 1 wasobtained. However, 0 was slightly observed in a Cu-based film in the EDSanalysis.

Example 13

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 except that(N,N′-Diisopropylaceto amidinate) copper dimer was employed instead of(N,N′-Diisopropylpropion amidinate) copper dimer. Thus obtained film wasalmost identical to that of Example 1. However, it took about 20% longertime in order to obtain the film thickness identical to that of Example1.

Example 14

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 using the chemical compound ofthe General Formula [I] (each of R¹, R², R⁴, and R⁵ was an iso-propylgroup, and each of R³ and R⁶ was an n-butyl group). Thus obtained filmwas almost identical to that of Example 1. However, it took about 20%longer time in order to obtain the film thickness identical to that ofExample 1.

Example 15

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 using the chemical compound ofthe General Formula [I] (each of R¹, R², R⁴, and R⁵ was an n-propylgroup, and each of R³ and R⁶ was a methyl group). Thus obtained film wasalmost identical to that of Example 1. However, it took about 20% longertime in order to obtain the film thickness identical to that of Example1.

Example 16

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 using the chemical compound ofthe General Formula [I] (each of R¹, R², R⁴, and R⁵ was an n-propylgroup, and each of R³ and R⁶ was an ethyl group). Thus obtained film wasalmost identical to that of Example 1. However, it took about 20% longertime in order to obtain the film thickness identical to that of Example1.

Example 17

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 using the chemical compound ofthe General Formula [I] (each of R¹, R², R⁴, and R⁵ was an n-propylgroup, and each of R³ and R⁶ was an n-butyl group). Thus obtained filmwas almost identical to that of Example 1. However, it took about 20%longer time in order to obtain the film thickness identical to that ofExample 1.

Example 18

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 using the chemical compound ofthe General Formula [I] (each of R¹, R², R⁴, and R⁵ was an n-butylgroup, and each of R³ and R⁶ was a methyl group). Thus obtained film wasalmost identical to that of Example 1. However, it took about 20% longertime in order to obtain the film thickness identical to that of Example1.

Example 19

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 using the chemical compound ofthe General Formula [I] (each of R¹, R², R⁴, and R⁵ was an n-butylgroup, and each of R³ and R⁶ was an ethyl group). Thus obtained film wasalmost identical to that of Example 1. However, it took about 20% longertime in order to obtain the film thickness identical to that of Example1.

Example 20

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 using the chemical compound ofthe General Formula [I] (each of R¹, R², R⁴, and R⁵ was an iso-butylgroup, and each of R³ and R⁶ was a methyl group). Thus obtained film wasalmost identical to that of Example 1. However, it took about 20% longertime in order to obtain the film thickness identical to that of Example1.

Example 21

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 using the chemical compound ofthe General Formula [I] (each of R¹, R², R⁴, and R⁵ was an iso-butylgroup, and each of R³ and R⁶ was an ethyl group). Thus obtained film wasalmost identical to that of Example 1. However, it took about 20% longertime in order to obtain the film thickness identical to that of Example1.

Example 22

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 using the chemical compound ofthe General Formula [I] (each of R¹, R², R⁴, and R⁵ was an iso-butylgroup, and each of R³ and R⁶ was an n-butyl group). Thus obtained filmwas almost identical to that of Example 1. However, it took about 20%longer time in order to obtain the film thickness identical to that ofExample 1.

Example 23

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 using the chemical compound ofthe General Formula [I] (each of R¹, R², R⁴, and R⁵ was an sec-butylgroup, and each of R³ and R⁶ was a methyl group). Thus obtained film wasalmost identical to that of Example 1. However, it took about 20% longertime in order to obtain the film thickness identical to that of Example1.

Example 24

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 using the chemical compound ofthe General Formula [I] (each of R¹, R², R⁴, and R⁵ was an sec-butylgroup, and each of R³ and R⁶ was an ethyl group). Thus obtained film wasalmost identical to that of Example 1. However, it took about 20% longertime in order to obtain the film thickness identical to that of Example1.

Example 25

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 using the chemical compound ofthe General Formula [I] (each of R¹, R², R⁴, and R⁵ was an sec-butylgroup, and each of R³ and R⁶ was an n-butyl group). Thus obtained filmwas almost identical to that of Example 1. However, it took about 20%longer time in order to obtain the film thickness identical to that ofExample 1.

Example 26

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 using the chemical compound ofthe General Formula [I] (each of R¹, R², R⁴, and R⁵ was a phenyl group,and each of R³ and R⁶ was a methyl group). Thus obtained film was almostidentical to that of Example 1. However, it took about 30% longer timein order to obtain the film thickness identical to that of Example 1.

Example 27

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 using the chemical compound ofthe General Formula [I] (each of R¹, R², R⁴, and R⁵ was a phenyl group,and each of R³ and R⁶ was an ethyl group). Thus obtained film was almostidentical to that of Example 1. However, it took about 25% longer timein order to obtain the film thickness identical to that of Example 1.

Comparison Example 1

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 except thatbis(diisobutylmethanato) copper [Cu(dibm)₂] was employed instead of thechemical compound of the General Formula [I] of Example 1. However, a Cufilm was not formed.

Comparison Example 2

The copper-based film forming method was carried out in a manneridentical to that performed in Comparison Example 1 except that aheating temperature by the heaters 7 was changed from 140° C. to 240° C.In this Comparison Example, a Cu film was formed. However, impurities ofC and O were observed in thus obtained Cu film.

Comparison Example 3

The copper-based film forming method was carried out in a manneridentical to that performed in Example 1 except thatbis(hexafluoroacetylacetonato) copper [Cu(hfac)₂] was employed insteadof the chemical compound of the General Formula [I] of Example 1.However, a Cu film was not formed.

Comparison Example 4

The copper-based film forming method was carried out in a manneridentical to that performed in Comparison Example 3 except that theheating temperature by the heaters 7 was changed from 140° C. to 240° C.In this Comparison Example, a Cu film was formed. However, impurities ofC, 0, and F were observed in thus obtained Cu film.

REFERENCE SIGNS LIST

-   1 CO₂ high pressure cylinder-   2 H₂ high pressure cylinder-   3 cooling device-   4 pressure pump-   5 mixer-   6 material container-   7 heater-   8 preheating chamber-   9 reaction chamber-   10 substrate-   11 back pressure governor

1. A method for forming a copper-based film on a substrate insupercritical fluid, wherein a chemical compound represented by thefollowing Formula [I] is dissolved in the supercritical fluid and copperis deposited on the substrate to form the copper-based film thereon.

wherein each of R¹, R², R³, R⁴, R⁵, and R⁶ is a hydrocarbon group havinga carbon number of 1 to 10, and wherein R¹, R², R³, R⁴, R⁵, and R⁶ maybe the same or may be different from one another.
 2. The method forforming a copper-based film according to claim 1, wherein the chemicalcompound represented by the Formula [I] is dissolved in a solvent andthen supplied to the supercritical fluid to be dissolved therein.
 3. Themethod for forming a copper-based film according to claim 2, wherein thesolvent is one or more selected from a ketone, an ether, and ahydrocarbon.
 4. The method for forming a copper-based film according toclaim 3, wherein the solvent is a ketone.
 5. The method for forming acopper-based film according to claim 4, wherein the solvent is one ormore selected from acetone, methylethyl ketone, methylpropyl ketone,methyl isobutyl ketone, methyl amyl ketone, diethyl ketone, andcyclohexanone.
 6. The method for forming a copper-based film accordingto claim 1, wherein each of R¹, R², R⁴, and R⁵ is an iso-propyl group,and each of R³ and R⁶ is independently selected from a methyl group, anethyl group, and an n-butyl group.
 7. The method for forming acopper-based film according to claim 1, wherein each of R¹, R², R⁴, anda R⁵ is an iso-propyl group, and each of R³ and R⁶ is an ethyl group. 8.The method for forming a copper-based film according to claim 1, whereineach of R¹, R², R⁴, and R⁵ is an n-propyl group, and each of R³ and R⁶is independently selected from a methyl group, an ethyl group, and ann-butyl group.
 9. The method for forming a copper-based film accordingto claim 1, wherein each of R¹, R², R⁴, and R⁵ is an n-butyl group, andeach of R³ and R⁶ is independently selected from a methyl group and anethyl group.
 10. The method for forming a copper-based film according toclaim 1, wherein each of R¹, R², R⁴, and R⁵ is an iso-butyl group, andeach of R³ and R⁶ is independently selected from a methyl group, anethyl group, and an n-butyl group.
 11. The method for forming acopper-based film according to claim 1, wherein each of R¹, R², R⁴, andR⁵ is a sec-butyl group, and each of R³ and R⁶ is independently selectedfrom a methyl group, an ethyl group, and an n-butyl group.
 12. Themethod for forming a copper-based film according to claim 1, whereineach of R¹, R², R⁴, and R⁵ is a phenyl group, and each of R³ and R⁶ isindependently selected from a methyl group and an ethyl group.
 13. Themethod for forming a copper-based film according to claim 1, wherein thesupercritical fluid is a supercritical fluid comprising CO₂.
 14. Themethod for forming a copper-based film according to claim 1, wherein thesupercritical fluid is a mixture of CO₂ and H₂.
 15. (canceled)